The Proteomics Shared Resource is a new Cancer Center SR that evolved from an established facility at CUMC with strong expertise in all aspects of sample preparation and mass spectrometric analysis that will be increasingly applied to cancer related research projects. The goal is to provide an essential battery of mass spectrometry-based proteomics tools to HICCC investigators. Specific services are to use state-ofthe- art experimental strategies for: [unreadable] Identification of proteins by in-gel digestion and mass spectrometry [unreadable] Identification of protein components within protein complexes [unreadable] Identification of phosphorylation sites and other covalent protein modifications Instrumentation in this facility includes two high-resolution quadrupole-TOF electrospray mass spectrometers equipped with nanoflow LC for LC-MS, and a MALDI-TOF mass spectrometer. A key activity will be education of researchers in the ways state-of-the-art proteomics tools can advance their research. The HICCC has made recent investments in the facility infrastructure, and has been publicizing the facility to HICCC members, leading to an increased focus on mass spectrometry for cancer research. However, currently the facility has minimal financial support for daily operating expenses from the HICCC and has raised funds for its continued operation by offering cost-effective mass spectrometry services to outside investigators. In this grant renewal we are proposing increased direct support for this Shared Resource. The facility will continue to have close intervhactions with investigators, advising them on experimental design, sample preparation, and data interpretation. Future goals include the implementation of quantitative proteomics techniques based on labeling methods coupled with LC-MS, and the expansion of the Resource to include a two-dimensional gel electrophoresis service. Gel-based proteomics will facilitate investigation of protein mixtures of greater complexity such as those found in tissues and biological fluids, and opens the possibility of finding novel diagnostic markers and therapeutic targets. During the last period of the CCSG (transitioning to Cancer Center management) 34% of the Columbia investigators using the facility were Center members with peer-reviewed funding, with those members representing over 30% of the utilization of the services. The proposed total operating budget of the facility is $380,006, of which we are requesting $84,858 from CCSG.